Chocolate marshmallow under vacuum

Fancy something sweet? Then this experiment is just the thing: place a chocolate marshmallow in a desiccator. As the air is evacuated, the chocolate coating bursts and the white foam inside expands to roughly twice its original volume. This latter process is largely reversible, so that the foamy mass shrinks again when air comes into the desiccator.
Please book this experiment at least three days in advance.