Thistle converted from a corner just before the hour mark with Tommy McIntyre side struggling to break through a defence that wasn’t fussy about how they kept their opponents out until Burt netted in the second minute of stoppage time.
After a stale opening half hour the game began to open up with Armstrong Oko-Flex the main creative force as he drifted in off the left wing with some purpose.
After 35 minutes Oko-Flex came in from the left, passed to Dembele but when the ball came back a Thistle defender managed to clear at the expense of a corner. A couple of minutes later Oko-Flex sent a dipping shot across goal before Thistle keeper Sneddon got down brilliantly to his right to push away a 20 yard shot from Karamoko.
After 59 minutes Celtic were taught a lesson in finishing when Mouhamed Niang found space at a corner to put Thistle in front.
Ten minutes later Oko-Flex struck the bar from close range with Jonathan Afolabi sending the rebound wide of the post.
In the 78th minute there was a let off for Celtic when Thistle netted from a free kick but for some reason it was disallowed.
There was no real threat to the Thistle goal but in the closing stages Burt drove down the right before shooting low across goal to earn the hoops a point.
CELTIC: Mullen; O’Connor (Savoury 45), Hjelde, Hendry, Church; Connell, Coffey (Murray 79); Harper (Burt 65), Karamoko, Oko Flex (Wylie 79); Afolabi
SUBS: Hughes, Paterson, McGrath