When it first appeared, the Soviet T-72 was quite impressive to our own US Army, still primarily equipped with the M60A1 tank. It had a larger main gun, lower profile, better weight-to-horsepower ration, and an innovative autoloader for the main gun.
But that last feature was also one of its weak points. The 125mm main gun of the T-72 uses a semi-combustible propellant case for its ammunition. That is, when the round is fired, most of the case burns during the shot, and only a small stub at the base is ejected. That’s not bad, in and of itself. The 120mm main gun of the M1A1 does the same thing. But because of the way the autoloader on the T-72 was designed, this combustible ammunition was arrayed on a carousel at the bottom of the turret basket, and exposed. That’s bad for the ammo, and really bad for the crew if there is any explosion aboard.
Watch this video of a Syrian Army T-72 being hit by an RPG. Soon after impact, the propellant ignites, and what should have been a damaged vehicle instead becomes a catastrophic loss.