Unless you're talking about slow motion, a real soap bubble basically just disappears. There will be a few little soap particles, but it really just goes POP and is gone.
However, I assume you mean you want it to blow up and disappear outwards. You could use a distort effect, such as Bulge. Coupled with Effect>Transition>Iris Wipe.
You'll need to adjust the parameters of the iris wipe to make it look round (make iris points a higher number), then feather it.
Assuming I assumed the effect you were after correctly, that should do the trick.
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The Scatterize effect may also work for your situation. To make it look good, you would most likely want to introduce a blur on the scatterizing (is that really a word) layer as the scatterizing is taking place, and enable motion blur for the layer and the comp.