Here it it is: they call it “supercritical opalescence”. Basically, if you have boiling water and air in an enclosed (pressurized) state, it will reach a strange point where there is a WHITEOUT and there is no distinction between LIQUID and GAS. This video goes up to the supercritical state and then back down again. So I think your idea of the surface tension definitely has strong merit – http://www.youtube.com/watch?v=29oy1UCHJIE “