My right ankle, sometimes my left, will become stiff and comfortable and the only way to get rid of the stiffness it to crack my ankle, is that normal?

Typically: a stiff ankle does feel better when you "crack" it. If it is a common occurrence, ever becomes painful or swollen you may want to see a Podiatrist for a further look and diagnosis. In some patients this can be a sign of previous sprains or injuries. Stay hydrated and stretch daily!

Cavitation.: Actually, the stiffness is probably relieved from the act of stretching the soft tissue elements, such as joint capsule, thus relieving the stiffness. The added consequence of the stretching is the affect of cavitation on the joint fluid. The stretching decreases the pressure within the joint fluid thus allows nitrogen gas bubbles to form. When the bubbles burst, you hear it as a pop. Go figure.