Well after 1 1/2 years of homrebrewing, I finally had a explosion in the basement. I brewed a extract Kolsch kit from Northern Brewer on Sunday. I used a 1500ml starter that sat on a stir plate for 3 days. When I left for work at around 3PM Monday the blowoff tube was going like crazy and the top of the bucket seemed to be curved out a little. Somewhere around 8-9Pm my wife said she thought she heard a noise from downstairs but just ignored it. The bucket was in a 60 degrees room and according to the stick on thermeter is was 60-62 degress.
After cleaning everything up and getting the cover back on the bucket, within 30 minutes it appeared it was getting ready to go again. I reopened the bucket and removed some of the krausen. It seems to be okay this morning. I guess I'll have to give it a couple more days and check the S.G.
This one was actually my biggest starter to date at 1500ml and my second time using the stir plate. I think the combination of big starter and not using a strainer when I dumped the kettle had a little to with this mess.