Crackling sound and a thin layer of something on the surface before water boils I washed my cooking pot and put some water in it, and put it on the stove.
When the water came close to boiling, I started hearing crackling sounds and there was a thin coat of some substance on the surface.   

I thought maybe the pot wasn't clean enough, so I washed it once again thoroughly, but the same thing happened again.
Then I used another pot and everything went fine.   

My question is, obviously, what was going on with the first pot, and how do I avoid it?
The obvious theory to me would be that there was still some oil in it, but I did wash it properly and don't even remember putting oil in it recently.

Edit: I'm using electricity to cook (the oldschool 3D round thingie, no glass and no induction) and the pot is made out of stainless steel.
The crackling sounds are not from the pot being wet, they're similar but a bit different (and the pot was dry).
 They could be from the pot expanding, but that wouldn't explain the thin layer on the surface of the water.  

Edit2: video
I am making a guess here, but a guess based on my own experiences.

You have an induction glass top stove, and you are putting the pot down on top of it wet. The water is getting trapped under the pot, and once it is able to reach boiling (just before the water in your pot does). It is starting to pop (like popcorn).

It pops because it is trapped. Because the pot is wet it gets "sealed" to the stove top, and the steam can't escape until it builds enough pressure to lift the heavy pot just enough for the gas to escape violently.

The way to make it stop is to dry the outside of the pot after you wash it and/or before you cook.