It was a question in one competition, but it remained unanswered and i am curious about an answer. There was a hint: American bullfrog but i can not find any example of this behaviour on the web.
The closest I can think of with that hint is a Middle Eastern beetle that hunts frogs and other amphibians:
In almost 400 face-offs, the amphibians only managed to get the larvae in their mouths seven times. Even then, they soon spat out the larvae, which quickly turned on them (first video below). One toad even managed to swallow a larva, which moved inside its stomach for two hours. For some reason, the toad eventually regurgitated its catch, and the larva, apparently unharmed, killed and ate the animal that had just eaten it (second video below).
However, it's only a pseudo-fit to the clue. The beetle doesn't hunt American bullfrogs, but ones native to its area of the world.
I think your clue probably leads to this video, which shows a rough-skinned newt (Taricha granulosa) consumed by a bullfrog (Rana catesbeiana). The frog then dies and the newt exhumes itself.
This is probably less likely in most settings since selection would quickly strike a balance between the prey's defensive toxin and the predator's immunity (for instance). This is probably more likely to occur in invasion scenarios wherein the predator is naive to the prey defense (for example).
The rough skinned newt is very poisonous and can kill frogs and climb out of them. using a cocktail of heart stopping, paralyzing toxins, it can kill a human too. http://video.nationalgeographic.com/video/weirdest-newt
Some frogs can make their predator vomit without killing them: http://www.cairnspost.com.au/free-from-the-jaws-of-death-frog-escapes-snakes-stomach-after-being-regurgitated/news-story/861879b553964ec75866dd6ae354a5bd
And the Epomis Larvea make a frog attack them and then bite it on the head, poison it and eat it, probably alive. https://www.youtube.com/watch?v=0y1FPm5WNVc
Some beetles can literally chew their way out of a venus fly trap using their mandibles, although perhaps that's less common in the wild. http://i.imgur.com/NGI5Z.jpg ... other pages on that topic http://www.flytrapcare.com/phpBB3/holes-in-my-plants-t28144.html http://www.flytrapcare.com/phpBB3/earwigs-giving-my-plants-problems-t6041.html this is the beetle that i confusedly watch eat its way completely out of the plant. they don't do that on tv! it took 2 days to escape. http://www.naturespot.org.uk/species/common-red-soldier-beetle