Bread poultice is very effective in drawing out boils from the skin.
Place a small pot of milk on the stove and heat. When the milk is warm (but is still at a temperature that can be comfortably applied to the skin without burning) remove the pan from the heat. Place a piece (or a few bite size pieces) of bread into a heat-proof bowl, and carefully pour the milk over the bread. Let the bread soften, gently combining the bread and milk until it reaches a paste consistency. Apply the bread & milk mixture directly to the boil and let it dry. Remove mixture. Repeat twice daily until the boil ruptures.