Liquid Nitrogen KABOOM

Liquid Nitrogen boils at -192 degrees Celsius.  When it boils inside of a 2 liter pop bottle, it expands rapidly and the gas creates so much pressure on the bottle that it explodes into a million pieces:

Liquid Nitrogen Graham Crackers

Liquid Nitrogen enters into a graham cracker's pores.  When you pull it out of the liquid nitrogen, it boils as soon as it comes into contact with the air.  It uses the heat energy from the graham cracker to do this, making the cracker VERY cold.  It gets so cold, in fact, that when you eat one, your breath condenses as water vapor, making it look like you are breathing smoke!