Imploding drinks can

 We put about 1 cm of water into the bottom of an empty drink can. Well, it wasn't really empty; it was full of air. We boiled the water strongly so that steam was coming out of the can for nearly a minute. This drove the air out of the can and now we had a can full of steam. Then we quickly flipped the can upside down into the bowl with one smooth movement. It was important to land the opening of the can into the water. The water quickly cooled the steam down so that it condensed. In the liquid state the particles took up less space so now most of the inside of the can really was empty. It was a partial vacuum inside. The can collapsed inwards with a bang.

A can is normally fine because air particles on the inside pushing outwards are balanced by air particles on the outside pushing inwards. With a partial vacuum the air particles outside have nothing to balance their inward push. The can implodes.