Brewed the pumpkin ale yesterday. I pitched the yeast late. When I first start a batch fermenting, I put it in the stationary tub. This morning it was chugging along. It wasn't anything violent, just a steady ferment. We went out for a couple hours and when I got home to check on it, I was shocked. It was no longer bubbling, it was hissing. The air lock was clogged. It was lucky that I checked it or it would have blown the lid off the bucket. I pulled the air lock, sanitised a blow off tube and installed that. It is one of the most violent fermentations I've ever had, even more than the wheat beers that I've done. Simply amazing.