If lightning strikes while you're going through a container or using a crockpot, the UI will close. Quite annoying during spring.
This should be a good example:
If a player is suddenly in complete darkness, they close any containers / crockpots which are active.
Screen flashes from lightning, gunpowder, etc count as complete darkness for a split second, so the container shuts.
This also happens on the non-multiplayer version of Don't Starve, It's especially bad during Hurricane Season in SW.
While having a container open and not being near a light source, force lightning to occur.