I have a 2001 Honda Accord LX Sedan. Just recently it started making a noise (like when your making popcorn) from the right side of the motor around the timing belt area. Its a low noise you can hear it when its at a stop. It only makes that noise when im on my way from work when the car is wamred up/hot. Before it started making this noise i got a brand new EGR Valve, Gas Cap, and Catalytic Converter & did a tune up.

 

Considering the bad consequences of losing a timing belt, you should probably remove the upper timing cover & have a look around.

Bad belt beginning to make noise? Change it quick before it breaks.

Tensioner pulley bearing? Waterpump? Any of that stuff can throw your timing belt & you end up with bent valves.

I had a very loose waterpump on a VW. It didn't leak, but when I loosened the belt I could wobble the pulley. It made a rattling sound a bit like you're describing.