If you put a wet marshmallow in the microwave, several interesting things can happen due to the unique properties of marshmallows and the way microwaves interact with them:
Expanding: When marshmallows are heated, the water content inside them turns into steam. This steam builds up pressure, causing the marshmallow to expand in size. It can grow significantly larger as the steam tries to escape.
Puffing up: As the marshmallow expands due to the steam, it puffs up and becomes softer and fluffier. The heat causes the air bubbles in the marshmallow to expand, leading to its characteristic light and airy texture.
Browning or charring: If the marshmallow is exposed to the microwave's heat for too long, it can start to brown or even char on the surface. This happens due to the sugars in the marshmallow caramelizing and forming a crispy outer layer.
Potential mess: The expansion and puffing of the marshmallow can be quite dramatic, and if it gets too big for the container you placed it in, it might ooze out or make a mess inside the microwave.
Uneven heating: Microwaves heat unevenly, and depending on the marshmallow's size and shape, some parts may become superheated, while others remain cool. Be cautious when removing it from the microwave to avoid burns.
It's important to note that microwaving marshmallows can be unpredictable, and results may vary depending on the marshmallow's size, moisture content, and the power of the microwave. If you want to experiment with microwaving marshmallows, do so cautiously and be prepared for some fun (and potentially messy) surprises!