From Nick Uhas:
I’ve done this reaction many times before. I did it for the Today show, America’s Got Talent, and a ton of live shows. So I’m pretty familiar with it, to say the least. And after our Elephant toothpaste experiment, I started thinking about other things we could do with the lifeguard tower and the super large water tank. So this got me thinking, we could use the same equipment, modify it slightly and do the world’s largest liquid nitrogen explosion… or what I’m calling the Liquid Nitrogen Mega Cloud. Also, my yard is too small for an experiment of this size so we’re heading over to the SWAY LA house since they live in a mansion and have the perfect setup for us.
Also, the reason this experiment works is that the boiling hot water is just about 212 (100C) degrees F and the liquid nitrogen is -321F (-196C). When the water gets in contact with the freezing cold liquid nitrogen it vaporizes instantly creating water vapor. This vapor builds pressure inside the trashcan and explodes outward in the huge plume.