sounds like your pump has more Output volume than your stone can allow to pass,therefore the bubbles come out extra fine & in large #'s.
there is probably a high sqeaky sound coming from the stone as well which is a sign that you are pushing to much air thru it.
As for the surface delay of popping that usually means there is excess dissovled organic's in the water Or also finer bubbles are more difficult to pop.
add another air stone of the same size to the pump or get a 2 way gang valve & connect 1 end to the stone & the other to open air.adjust #2 valve to adjust bubble rate.
prob should get a 4 way valve which would allow for more connections later.(just close the ones not in use)
IMPORTANT....each line after the gang valve control needs a check valve.if all lines go into the tank(underwater) then only 1 is required on the line between pump & valve,But if 1 valve is being used to lower pump output(venting to the air) then each line into the tank needs a check valve between the valve & the airstone/decor item.
what this does is lowers the pumps output (better for pump life)
get the bubbles under control then see if they pop better.