Having said that I’ve never seen or hit a bubbler.
I really don’t get the point of them, as of any bong smaller than 16"
What I mean is that I really don’t like it when the smoke reaches your throat before you’ve cleared the bong, it makes it much more likely for me to cough badly. And that is unevitably going to happen if the pipe isn’t big enough to hold your desired quantity of smoke.
So I really don’t see the sense of them since it seems to me that you either take very small hits or your going to cough, and taking small hits just seems against what I think is the whole point of bongs, a big dense instantaneous hit of smoke.