A can of soda can explode if you leave it in the freezer for an extended period and then open it due to the process of freezing and the expansion of the liquid inside.
When you put a can of soda in the freezer, the liquid inside (which contains water, carbon dioxide, and flavoring) starts to freeze. As the temperature drops, the water molecules in the soda turn into ice, and the carbon dioxide gas dissolved in the liquid forms tiny ice crystals as well.
Here's what happens next:
Freezing of water: Water expands when it freezes into ice. The expansion can exert tremendous pressure on the container, in this case, the aluminum can. Aluminum cans are generally quite strong, but they do have their limits.
Pressure buildup: As the soda freezes, the ice and carbon dioxide gas continue to take up more space inside the can. This causes the pressure to increase significantly, since the can is not designed to handle the expansion caused by freezing liquids.
Can rupture: Eventually, if the pressure inside the can becomes too high, it will surpass the strength of the can, leading to a rupture or an explosion. This can happen even if the soda hasn't completely frozen, as the pressure can still build up to dangerous levels.
Opening the can: If you then open the can after it has been in the freezer, the sudden release of pressure can cause a more dramatic eruption of soda, potentially resulting in a messy and fizzy explosion.
To avoid this, it's essential not to leave carbonated beverages in the freezer for extended periods. If you accidentally do so, allow the can to thaw gradually in the refrigerator or at room temperature before opening it. Alternatively, you can gently tap the sides of the can to release some pressure before opening it carefully. Be cautious, as even partially frozen carbonated beverages can still have elevated pressure levels.