What you'll need:
Dry ice
Water
Mixture of soap and water
Bowl
A strip of material or cloth
What to do:
Place your dry ice into the bowl and pour some water. Dip the material/cloth into the soapy solution and run it around the lip of your bowl, and then drag the material across the bowl.
Step away from the bowl and watch you bubble grow!
Precaution:
Dry ice can cause skin damage, so handle it very carefully. It is better to use gloves.