Re: This theory always puzzles me
You still need nucleation sites. For gas to spontaneously form bubbles within the bulk liquid is actually very difficult due to energy constraints, this is why when you open a bottle of sparkling water you typically get a pop, but it doesn't usually (if it's been standing for a while) transform immediately to foam. Typically bubbles actually grow from microscopic nucleation sites, which might be microscopic bubbles in the bulk, surface irregularities of the container, turbulence and suspended particles.