I had a yeast starter on a stir plate that made a really intense kraisen. I installed a blowoff tube and put the other end into a jar of sanitizer. Later, after it had fermented out, I put the starter, with blowoff tube still submerged in the jar of sanitizer, into the fridge to crash cool. I found out later that a siphon had started and sucked a bunch of sanitizer into my starter.
Can someone explain this to me, it seems that the pressure inside the starter would have to fall below atmospheric. Does this really happen?