Loud noise on starting

[nj1]

I just tried to start my car after almost 4 months, battery voltage was low and fuel pump primed but wouldn't crank over but heard a loud pop like a gunshot and then battery completely died. I tried to get it to crank over several times.

I Replaced the battery and it started up fine. 

Should i be concerned about the loud pop noise? 

I can't drive the car due to it being a unregistered track car to see if there is an issue but as i mentioned it seems to idle fine. 

[Manuel Kasko]

Check the fuses? 
Might have been one of those popping

Is everything else working fine? (aircon if you have it, lights etc)

[tridentt150v]

Probably unburnt fuel in the system.  Wouldn't worry about it.

[RBBACKR33]

Oil in the turbo from last track day drive? Did it blow out any black or blue smoke after the pop?

[nj1]

Seems like just unburnt fuel in the cylinder from cranking over a few times unsuccessfully.

No smoke or anything just a very loud pop from out the exhaust...didn't sound like it emanated from the engine bay