When we made small dry ice bombs to blow up pumpkins, we were making use of these unique behaviors. Dry ice is solid carbon dioxide with a temperature of - 109°F. Applying energy to dry ice causes the molecules to phase change straight from a solid to a gas, sublimation. When gas particles hit the walls of a container, they exert pressure. As we apply energy to dry ice, the gas molecules move faster which makes them smash into the container walls more often and with more force. The more they smash, the greater the pressure. If these smashing molecules are in a confined space/volume, dry ice bomb and pumpkin shards.