Splashing rats but getting no XP? game breaking bug? wtf is going on

So over the past few days I've been splashing rats using chaos runes to try and get my magic level up. Finally got to about 76 today, going for about 82 so I can start using wrath runes. But I noticed something crazy today. I'm splashing away for literally like an hour and haven't gained a single XP. Wtf is this? How can I be splashing and casting hundreds upon hundreds of spells for over an hour and get no XP at all?