What can happen is that the nerve inside a tooth can die and
abscess leading to drainage into the gums which creates the
gum boil. It might bleed and can be purulent (pus releasing) or not. The other situation is if there is a localized area of severe periodontitis (gum disease). That can also result in a gum boil. The dentist will check out the area, take an xray and be able to tell you what can be done, either possibly a root canal ,deep scaling/curettage, extraction, referral, etc.