Diagnosis
That's a small gas flare-up, usually because there's a tiny delay between gas flowing and the igniter spark catching it, allowing a small pocket of gas to build up before it ignites all at once. It's common, especially if you turn the knob too slowly or if there's a slight breeze.
How to Fix It
Use a more assertive lighting technique. Turn the knob for the burner you want to light to the High position firmly and quickly. Don't hesitate. The clicker should start immediately, and the gas will ignite as it flows. Make sure the area under the griddle is clear of leaves, spiderwebs, or grease that could also ignite.
If That Didn't Work
If it's consistently one burner popping loudly, the spark might be weak or mis-timed. Check the electrode gap and connection for that burner (see the 'burner won't light' fix above). A stronger spark reduces the chance of delayed ignition.
Heads Up
While startling, a single small pop isn't typically dangerous. However, if you smell gas without lighting, or if the flame doesn't establish after the pop, turn the knob off immediately, wait 5 minutes for gas to disperse, and try again. Never hold your face directly over the burner when lighting.