I have ready in a few places that, when you feed your starter, it should be covered "loosely."
Well, I have never done that, always just using a round Cambro 1 quart container - putting the lid on it and moving on.
Yesterday, I took my neglected Ischia out of the fridge and it, 1 part starter, 1 part flour, 1 part water - totaling about 16 ounces. I put the lid on and left it on the counter. By evening, it had barely budged (not surprised) so I left it on the counter overnight. This morning, sure enough, the starter had risen all the way to the top of the container and had overflowed all over the counter.
No big deal. I took it over to the sink so I could wash the outside of the container and give the starter another feeding.
The lid popped off the container with a bang and flew about 8 feet to the other side of the room. Luckily, most of the spillage was in the sink (and on my cheek and eyeglasses).
So, now you are warned.