See Bathing, Washing.
Depth Psychology: A soap dream encourages a process of self-cleansing and freeing yourself from an old guilt. Soap bubbles mean you are entertaining too many illusions and the bubbles will burst soon.
The dream wants to warn you that there is nothing there for you to hold on to—the illusions will come to an end. Foam is a symbol of churning emotions like Aggression, Anger, or Rage.