Last weekend i was brewing a porter for winter. everything went well, was hitting my numbers within reason. i decided to boil for 90 min to bring up the ABV with about 15 min remaining i ran out of propane just after i added a whirlfloc tablet. not a problem as i always have at least one extra full tank. I hooked up the new tank but struggled getting the burner lit (hose wasnt seating on the tank properly. user error). after about 3 min of fussing the the tank, i got it working and the burner lit. I then added my aroma hops and when the boil resumed, the kettle almost boiled over!! the bubbles/foam was not as thick/protein rich as a normal hot break, but still concerning. I have never had this happen before. any thoughts as to what may have caused this?