Gas oven starts with BOOM!!!

We have an older Sears natural gas stove/oven. In the past few months,
when you light the oven, by turning the gas on (it has a pilot light),
it doesn't light right away. It might take up to 30 seconds and then it
comes on with a BOOM!! Sometimes it causes the door to fly open a
couple of inches.
What could be causing this??

I agree with John, clean the burner especially near where the pilot
light is. If you can take it out to clean it that would be better.

Gas is building up until it comes in contact with the flame. Your burner
probably needs to be cleaned.

geeez, i turn the gas immediately off & wait if it
doesn't ignite within 5-10 seconds (tops) - but to
wait 30 seconds ???? accident waiting to happen -
the fact it blows open the oven door should be a
BIG clue !! unless you want the Darwin award, that
oven should not be used - period - until it's
properly repaired/cleaned.

Reminds me of an old Bugs Bunny episode - with
the gangster hiding in the old house on the hill,
and the cop at the door, with our hero Bugs hiding
the mobster in the oven - then telling the cop,
"would I throw a lighted match in the oven if he
was in there?"....then holds the oven door shut
while it blows up inside.