Dry Ice Bubbles

Stir up some bubble, bubble, toil, and trouble using dish soap, water, and dry ice. For safety, keep kids away from dry ice pellets, which are extremely cold.

http://www.marthastewart.com/862757/dry-ice-bubbles

Dry ice available from your local ice distributor or for free as part of your frozen steak (or specialty food) mail-order packaging.