Not to mention they are designed that way on purpose. Optimal stoichiometric rise in jet fuel is approximately 1/8 to 1/3rd 600 degrees C. Boeing engineers have been scratching their heads for years on how to integrate conformal tank heaters into their high efficiency wings. They have never had a good way to do it. That is, until the Max 8 came along.
With it's high valved triple bypass engines mounted forward and above the wings, laminar heat rise was achieved over the #3,4,5 and 6 ribs. By integrating titanium into the proximal rib face, they were able to capture that heat and transfer it to the fuel in the tank.
This heats the fuel and while it does indeed explode, it's controlled similar to the gas in your car's cylinders. It's routed through the rotating vanes and valved back into the engine's bypass, increasing efficiency while also lowering the potential for a fuel tank rupture when operating in high alpha fan regimes.
Another neat little bit of tech integrated into the Max 8 is the fusible control surfaces, but that's a discussion for another thread...