faint knock when pulling in and out

[irondiezl3]

this is wierd and very hard to explaine. when i pull out either reverse or forward it makes a sound when almost near a dead stop it makes a popping. sorry hard to explaine. i cant tell if its like the strut making noise or maybe the caliper. again it only does it when i first pull out or first pull in and only one time then never again. wtf can this be its driving me insane.