I've had this happen to me at least 6 times on my Escort.It's from track use and is always on the passenger side,as most tracks are run clockwise.I've also had the threaded end of the outer CV joint break clean off twice.Now that is scary,as basically the only thing left holding the wheel on is the brake caliper over the disc!!!!!
The bearing's are always ok.At 1st I used to fit a new wheel bearing when replacing the hub,but it never stopped the hub from breaking.So then I didn't bother replacing the bearing.
I actually got so used to it happening that I could notice a different sound coming from the passenger corner,so would come in off track,strip down to the hub to see it was cracked.This saved me the possible danger of a failure on track leading to an accident or a tow in from the recovery truck.
I used to bring a spare hub,wheel bearing and outer CV joint to every trackday as part of my spares kit.Could strip and replace the hub in 30 mins easy I got so used to it.
Ahhh,the good old days,when I could afford to get the car out on track!!!!!!