There has been a lot of discussion on the forums here over the years about just what happened to Shinji in the Artificial Evolution Lab. I haven't read all of these linked discussions; I wonder if this forum has a consensus on what happened in the Lab or if it's all speculation.
Edit: Sorry I didn't make it clear in my first post in this thread, but the connection I'm drawing is that a lot of NERV procedures involve submerging subjects in LCL or dipping them into a core, so it makes sense to me that if these procedures happened to infant Shinji at the Artificial Evolution Lab, he would be unconsciously reminded of them as a teenager by an ordinary bath.