That motion, called convection, is what creates strong magnetic fields at the poles and smaller, local magnetic fields at the surface of the sun.
That instability causes havoc in the magnetic fields at the surface of the sun, which become much more active.
As the sun's local magnetic fields get more tangled and crash into each other, they can explode.
The worst solar storm we've seen happened in 1859.
But as SpaceX and NASA aim to ramp up missions in coming years, they will need to prepare for solar storms.