Dry ice is frozen, compressed carbon dioxide gas and when you add it to warm water, it combines with the water to create the fog (carbon dioxide and water vapor) that you see bubbling out of your cylinder. Adding soap to burping, bubbling, smoking water creates a whole new effect.ry ice is frozen, compressed carbon dioxide gas and when you add it to warm water, it combines with the water to create the fog (carbon dioxide and water vapor) that you see bubbling out of your cylinder. Adding soap to burping, bubbling, smoking water creates a whole new effect.