"Self-destructing messages" are mostly BS. There's no way to ensure the message is ever really gone, and most apps require all your friends to sign up just to share messages. Kaboom for iOS and Android solves at least the latter problem, by letting you share those timed messages anywhere, with anyone.
Once installed, you can craft your text or photo message, and tell the app when you want the message to "expire," or self-destruct. You can tell the message to vanish in as little as a few minutes (the clock starts after the message is opened by the recipient) or in months or years; it's entirely up to you.
Then, instead of only being able to share the message with other Kaboom users, you can share your message using any social network or messaging service you want. Twitter and Facebook work, or you could use WhatsApp or Hangouts. You could even use plain old email or SMS, or copy a direct link to your clipboard to send manually however you want.
The big feature is that you get the whole self-destructing message thing without forcing all your friends to use the same service you do to take advantage of it. Plus, it doesn't require Kaboom to be super-popular just to be useful.
Kaboom is by the same folks behind the freemium VPN Hotspot Shield, which I mention not as a nod to its security, but just to explain that it's a mature product. Like any self-destructing message service, you have no guarantee that your message is really gone, or that the person you sent it to hasn't downloaded it, saved it, screenshotted it, or whatever.
Kaboom doesn't talk about encryption or security, or promise the message isn't stored somewhere on their servers. Keep that in mind, and use apps like this for fun — not for truly secure communications.