In block 124724 you'll find txid 5d80a29b which has a payout of 49.99999999 BTC at a time when the block reward was 50 BTC. A transaction fee of 0.01 BTC was also forfeited. This bitcoin no longer exists anywhere in the network, as opposed to "burned" coins which technically still exist in a wallet which no one can ever access (ex: 1BitcoinEaterAddressDontSendf59kuE).
On bitcointalk user midnightmagic explains a deeper meaning behind this:
I did it as a tribute to our missing Satoshi: we are missing Satoshi, and now the blockchain is missing 1 Satoshi too, for all time.