You don't want the water to be boiling, but it should be very warm. You can also use a sink or anything large enough to hold a bowling ball and enough water to submerge it. Whatever you use will soon be holding a lot of oil, so take that into account.
Don't fill the bucket too much. The four-quart bucket shown above should be filled approximately halfway. Remember, you still need to put a bowling ball in there, and you don't want to flood your house.