I suggest you ask your doctor to take a look at them during your next checkup. Bumps, ridges, discoloration, or any odd change in texture or color of your nails indicates either your nails aren't healthy and are not being taken care of properly...or there is some sort of medical condition you are not aware of.
Until your next check up, try the these tips...
-Keep your nails clean and dry. -Avoid biting or picking your nails. -Apply moisturizer to your nails and cuticles every day. -File your nails in one direction and round the tip slightly, instead of filing to a point. -Don't remove the cuticles or clean too deeply under your nails, it can lead to infection. -Don't dig out ingrown nails... this is something a dermatologist should handle if it becomes a problem. -Avoid nail polish removers that contain acetone. -Bring your own tools/kit if you get manicures, to avoid infection. -If you use fake nails, check regularly for green discoloration (a sign of bacterial infection). -Eat a balanced diet and take vitamins containing biotin.
It could be caused from some previous internal finger or hand trauma that is growing out through the nail bed causing this bump to move upwards until it exits through the tip of the nail bed. I suggest you get it checked out by a doctor.
how bumps have you got? what do they look like?