When I brewed my very first beer, an old ale, I didn't have a blow-off tube. We'd just moved into a new place, and the basement -- which is where I was brewing -- was still a mess. I brewed on Saturday when my wife was at work (graveyard) and slept in on Sunday. When I got up at around 9:00 am, I decided to go clean up the basement. I was down there for a few hours when she came down and commented on how clean it was. Just then, I peeked into the corner where I'd left the bucket and noticed that the lid had blown off and there was beer all over the place.
"Oh," she said. "That must have been the explosion that shook the floor."
"Huuhh?????" was all I could say.
"Well, after I came home from work, there was an explosion and the floor shook, but when I went downstairs things looked fine, so I thought it might be nothing."
Shortly after that, we came to the understanding that if there was ever again an explosion that shook the floor, I was to be notified immediately. We DO have a gas furnace.