Mitch's mom

It sounds like it may be a burr on your hook. As it catches the thread on the down stroke the burr is holding onto the thread on the upstroke of the needle causing a loop of thread, as the hook comes around it tightens the loop causing the thread to remain on the hook. On the next pass, as the needle is on the downstroke, it allows enough slack for the thread to slip off the hook causing your 'ping' sound and creating a length of thread caught up in your stitches. If you have a piece of fine Emory cloth you can maybe smooth it out. The easiest way to find out if you have a burr is get a piece of a pair of pantyhose and run it over the hook. If there is a burr you'll know it.