When my water heater lit it would pop. Sounded like someone tapped the wall. Blow out those fuel lines going to heaters etc. spiders like to make webs inside and it restricts fuel flow. There is an opening just before where the flame lights.
While you are at it remove the cover for your refrigerator back on the outside of the rig and inspect for dust leaves etc. If you have compressed air blow up the rear of your fridge, watch the dust etc come out of the roof vent. Your fridge will thanks you for it.
Compressed air is a great way to maintain your rig. I always go nose to tail blowing dirt and debris out of everywhere. Blow on those seat cushions and above the window coverings. nice.