Pool Leak

Hi, I have yet another pool leak. Last year I fixed a return line leak in my spa, under concreate, pretty big job.

I have my gunite, inground pool professionally closed (live in Michigan). I open it myself. This year when I opened it and pulled out the line plugs, a line in the spa had water pooring out of it! What does this mean? I don't know why I keep having problems with pool lines when I have pool professionally closed.

I have noticed my return line in my spa bubbling when the pool is OFF! Is this a sign where the leak might be?

Thanks,
Elle