am not 100% sure of the trigger but it seems to have something to do with leveling up from level 1 cooking to level 2....has happened to 3 of us on server now already. I have also seen others post about it.
At time I was at level 59 about to go to level 60. I started cooking ( 1 chunky beef soup, 1 bowl of stock, 4 bowls of ramen). My cooking level went from 1 to 2 and when it did my level went from 59 to 60 and my points went from (46-low 50's, not 100% sure on this now) to 833.
The 2 others it has happened to on server I play on had similar experience. Not sure of XP levels but cooking was going from 1 to 2.