What does detonation sound like?

I got my trans pan back on today (another thread coming on that) and was driving the car around to check it out and under a light load going up hill accelerating barely had any throttle in it just enough to accelerate up the hill running appropriately 2k rpm around 30 mph I heard a pretty load popping sounded to me like it was back firing out the exhaust it did it maybe 3 or 4 times and I immediately let out and it stopped? I know im pushing the limits on pump gas with my compression. Do you think this is just a carb issue and it was backfiring ? I have never heard detonation to know what it sounds like. Thanks
From my experience, it sounds like pea gravel rattling around in a can.