In my experience, going past the max fill line is mostly a problem when using the “rapid pressure release” on a recipe with lots of liquid. Pressing the release button can emit a a superheated geyser of soup with enough force to hit the ceiling.
Another thing you know but may not have connected: this is exactly the same process that can make water "explode" if you reheat it in a microwave.
You don’t want to be nearby when this happens.
Water is only converted to steam while there's energy for it, so only a fraction of the water actually boils*. The risk is that it's a rapid process that propels a lot 100C water outside of the vessel.
*) I haven't done the full calculation, but I'm pretty sure the upper bound is something like 10%, with 2-4% being the best most normal people could accomplish in a microwave.
Plain stainless steel pot, small, good condition but still a couple years old. You'd think plenty of nucleation sites, right? Filled it with 195F water from the insta-hot tap, and put it on my induction stove and turned it on high to push it up to a roiling boil. But after 30 seconds -- nothing. Not a single bubble in the pan, which is weird all by itself. And at this point the range is pumping a fairly ridiculous amount of energy into what is already hot water.
So I thought "it can't really be superheating, right? on the stove??" and then grabbed the pot and swished it really good while stepping back. Sure enough, it instantly erupted into a furious boil.
I'd guess I'm unlikely to ever run into that situation again. The stars had to align pretty well, I think.
It takes 30-45 minutes to cool down enough to depressurize, but the lid is always clean so the food is likely staying in the pot.