I noticed the sound of running water behind my fridge today near the bottom & freezer failing.. Whats it mean?

It was working fine and then I heard this sound. Upon opening the freezer door, I noticed things were thawing. I removed all the items and the water running sound happened less often. I reloaded the freezer minus a few things and have not heard the water running sound again. Can anyone tell me what that sound might mean, and why it stopped after reloading everything?