When ever i bend down, or stand up or laugh or cough, it feels like bubbles going up my spine from my lower back. i feel no pain. what causes that?

Tiny bubbles...: Any clunks, clicks, snaps or pops that are not painful, are likely of no consequence. Though the exact cause of your bubbles may never be known, i suspect it is soft tissue. As we age, areas of friction, including joint cartilage, can develop calcium deposits. This creates a roughened surface that may feel as though it clicks or bubbles as the tissue glides against the underlying bone or muscle.

Wow: Thats a really strange symptom! you could have something really unusual like an arachnoid cyst, dural fistula, etc. Get seen by a neurologist or neurosurgeon.