In the latest episode of Outrageous Acts of Science, The Science Channel asked a team at Syracuse University to recreate a popular experiment in which molten lava is poured over a block of ice, causing the rapid formation of a mess of lava bubbles. The bubbles are formed when the extreme heat turns the ice into steam, which attempts to dissipate through the lava.
As the lava cools, we start to get a thick, black layer forming on top. That starts to trap those bubbles of super heated steam inside the rock. It’s kind of like a natural form of glass blowing.