It looks like frozen smoke. And it’s the lightest and lowest density solid material on the planet. Aerogel insulates space suits, makes tennis rackets stronger and could be used one day to clean up oil spills.
Aerogel is made by removing all liquid from silica gel whilst leaving its molecular structure intact. You’ve probably seen silica gel already- you get grains of it in those tiny packets labeled “DO NOT EAT” which you find in things you’ve bought. Inside the aerogel being held in the hand are millions of tiny nanoparticles of silicon dioxide, the same stuff that makes up sand and glass, interconnected.
If you were to take 1g of aerogel and flatten out its nanostructure, you would have something covering the size of an American football field. However, it would be pretty difficult to do that- aerogel can hold up to 4,000 times its own weight in force.
And yes, in the second GIF above, that IS somebody blowtorching their hand. The only thing separating hand from debilitating hand-death is a thin sheet of ridiculously efficient thermo-insulating aerogel- it’s a terrible heat conductor.