I feel like I know this word, but I can't think of it.
Here's the setting. I worked in the school's lab, where I was creating an ester from methane acid + methanol, and I dropped some sulfuric acid into the reaction tube, which made the contents bubble and kind of lightly erupt from the tube. Erupt is not the right word because it implies much more volatility than what the eruption really was.
This spillage was somewhere in between a gentle bubble over and volatile eruption. It was kind of like a few pulses of the liquid popping out of the tube, but not all of it erupting out.