Same way that pooled mining always works:  You attempt to mine a block, if you produce work which is less than some target set by the pool (which is a much easier bar than the network difficulty) you submit that work to the pool, and they decide if they like it or not, and then credit you based on how many of these shares you return. The shares constitute compelling evidence that you are working on work which is agreeable to the pool.

The pool could demand any level of disclosure and validation that it wants, but it really only needs to check that the coinbase transaction is correct. Any miner could always selectively throw away solutions which have hashes low enough to be valid blocks in order to attack the pool (this is called a withholding attack), so maliciously invalid blocks aren't an additional risk.

P2Pool goes all the way and replaces the pool with a decentralized system, but you don't have to go that far to still remove pools from the business of controlling the Bitcoin consensus algorithm.