T.S.
LOL. My son did the exact same thing when he was little. Even with checking his mouth, I swear I'd find him twenty minutes later, finishing off a little something he'd stored away. He would also try to shovel so much food in his mouth, he would have to hold his hand over his mouth while he chewed to keep it from falling back out!
My only advice is to make her swallow without driving you both crazy. Instead of checking after every bite... have her eat a bit, then offer some thing to drink, then check. Also, have her open wide and show you, rather than you reaching in her mouth so she stays in control.
Good luck.