Weird fermentation?

Ok, so I made 15 gallons of a russian imperial stout yesterday that I have done several time in the past. The beer is bubbling away just fine, but when I swirled the carboy today it erupted and blew the airlock off and went crazy all over the counter it was on. I tried the same thing with the other two carboys and got the same result. After about 5 minutes it settles down but when I swirled it another time the same thing happened.the OG was 1.115, any thoughts?

 

Why are you swirling the carboys?
When you swirl them, also called rousing the yeast, you off gas a lot of CO2. In an actively fermenting beer that might cause an 'eruption' like you mention. Not the greatest thing to do until fermentation is stopped or near stopped, though.

 

Slow learner?

 

I've been brewing for nine years and have several hundred brew sessions under my belt. I've never seen this happen before! I just shook it a little and it literally blew the little cup out of the air lock and then blew the air lock, stopper and all, out of the carboy, it was extremely violent! I was just shocked is all.

 

I've never seen that before but I can only imagine it is from the Co2 suspended in the beer. Ever shaken a beer before? Same thing!