How can a fluorescent light work temporarily with an open circuit?

I'm a new tech in avionics, troubleshooting a blown light that is ran in series. I was told to swap the light with the one ran inline with it. In response I told my supervisor I didn't think it would work, but I'd try it. I swapped the lights, and to my surprise it now flashed on momentarily. I then tried it with the other end completely open, only one connection to the light, and got the same result.

This just doesn't make sense to me. How is it possible for current to flow in an open circuit?