It depends on where the boil is located on your body. For example I had a boil on my private part right on my left lip. The first time I got it I went to go see a doctor because it actually gave me a fever and I limped in stuff. Come to find out I had to go into surgery just to get rid of it. I was sleep through the whole process. The second time I got it I went to the doctor again this time it was the same spot and I was awoke. Ugh it was so irritating. They stuck me with a needle inside of it then took a 4inch blade and some of this bring stuff and cut it. After they patched it which is actually the most irritating part. Third time I caught one I just sat it thorough and It popped on its own well drained.My advice is use antibiotics,soak in hot water or go to the doctor if you want it gone ASAP!
There isn't any one thing that can be said about it, they just show up. Sometimes it just happens, the only thing you can rally do is see your doc, or get rid of it yourself. Ouch, sorry. Hope this helps.