Is that the pot you intend to use? I would guess the base is warped on it. It looks like an electric stove, check to ensure the burner is stable and installed correctly. My boil pot wobbles until it gets hot then it is stable.
How much water is in it? Did you fill it up with the amount of water you need for a batch or did you just fill it full? There isn't a lot of room for foam when boiling there. You would need to watch that pot like a hawk so it doesn't boil over.