system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: when pouring soda into a cup of ice, why does the ice sometimes trigger massive amounts of bubbles, while other times hardly any?

It seems to happen with no rhyme or reason and wondering which variable is the cause ... cup material? ice shape/size? soda temperature? something else? I can't say I've found any common denominator in the many years this has confounded me.
gpt
I think it is the same effect as mentos. Nucleation (the bubbling) occurs with a hard surface. So fresh frozen, very dry ice will fizz more than say, ice that’s had the opportunity to melt a little and the surface smooths out.