CO2-driven water Eruption #1
    Exp #89 in Zhang et al. (1997, J. Geophys. Res., 102, 3077)
    The movie shows the slow motion of the experiment by a factor of 133.  A close-up view of the eruption front is shown.  The whole height is only 2.6 cm.  Initial test cell pressure was 5 bar, and tank pressure was 0.11 bar.  A polymer was added so that the viscosity is 18 times that of water (18 millipascal-second).  You can see the oscillation of the front at the beginning of the experiment due to shock wave reflection.  Only in such close-up views, are individual bubbles clearly distinguishable.  Almost all bubbles appear at the same time.  That is, bubble nucleation is instantaneous, lasting only ~ 1 ms.  Very few bubbles form before or after this event.  This is confirmed by the similar size of the bubbles.  Bubble growth data were obtained from such experiments.  Even though there is a rapid vertical flow, bubbles are not stretched vertically.  A nice foam forms and is stable.  You may think that there are bubbles inside bubbles.  These are actually bubbles behind bubbles.  You can see that bubbles near the center rise more rapidly than bubbles near the wall.  Near the end of the film, there is some coalescence.
 A foam is defined as a bubbly liquid in which the bubbles occupy more than 74% of the volume (i.e., the vesicularity is greater than 74%).  In a foam, the liquid is the continuous phase and the gas is not, even though gas bubbles account for most of the volume.  Greater than this vesicularity, spherical bubbles have to deform into polygonal surfaces in order not to break.  The deformation of spherical bubbles to polyhedral bubbles accounts for the honeycomb appearance of the foam.

CO2-driven water Eruption #2
    Exp #90 in Zhang et al. (1997, J. Geophys. Res., 102, 3077)
    The movie shows the slow motion of the experiment by a factor of 133.  Again a close-up view of the eruption front is shown.  A polymer was added but the viscosity is only 5 times that of water (5 millipascal-second).  Initial test cell pressure was 5.2 bar, and tank pressure was 0.07 bar.  There was a foam layer on top of the liquid column before the experiment, simulating the case of a magma chamber with a top bubble-rich layer.  Because of this bubbly layer, the eruption starts very violently.  Individual bubbles can be seen clearly and bubble growth data were obtained.  Bubbles are nicely spherical and not stretched vertically.  A foam forms but is not very stable.

CO2-driven coal outburst Experiment #1

    Exp #5 in Guan et al. (2009, Geology, 37, 915-918)
    The movie is a normal-speed video for coal outbursts using Dashucun coal pressurized by CO2. The initial length and diameter of the coal cylinder are 90 mm and 16 mm, respectively. The coal sample was pressurized by CO2 at 1.9 MPa for 89 hours prior to decompression. The movie records the processes at and after decompression. About 22% of the coal cylinder was fragmented after decompression. The thick line behind test cell is copper tubing (connecting test cell to vacuum pump).

CO2-driven coal outburst Experiment #2

    Exp #102 in Guan et al. (2009, Geology, 37, 915-918)
    The movie is a normal-speed video for coal outbursts using Wutongzhuang coal pressurized by CO2. The initial length and diameter of the coal cylinder are 91 mm and 25 mm, respectively. The coal sample was pressurized by CO2 at 4.0 MPa for 70 hours prior to decompression. The movie records the processes at and after decompression. About 73% of the coal cylinder was fragmented after decompression.