I have a small bony lump just above the normal big lump at base of back of neck. When I apply pressure to it it will pop in at times?

IsYourNameQuasimodo? Don't press too hard,your head'll fall off!! OK,now that we got that out of the way...My guess is that it's just a part of normal anatomy of the spine.The spiny part you a referring to has ligaments & other fibrous tissue/cartilage on top & you may be feeling that, especially if it feels kinda slippery and moves.So stop doing it or it'll start to hurt.Check it in a month, if larger get it checked.