We all know that when you boil milk it creates a foam and pours over the oven but to avoid that you can oil the inside edges of the boiler(container)
and it won't boil over:D!
If you put on the bottom of the pan a small inverted saucer, it will retard the process of foaming and rapid boil. When heated, you'll hear the rattling of a saucer on the bottom of the pan. Milk with this method will never run away. As a "watchman" of milk, you can use a lid for canning, put the bumpers down. It is under the cover will have a sufficient amount of air, which when heated will expand and go up, destroying the foam.