As switch and shypike said, there's no point. We have to send your password in cleartext. If we have to send it in cleartext, then there's no reason to encrypt it, because we'd also have to decrypt it. If we can decrypt it, it has to be trivial for anyone else to decrypt it. And even if we
did find some magical strong way to encrypt it, we'd still have to send it to your host in cleartext, which means a local attacker - even one not necessarily with physical access to your computer, just physical access to your network - could intercept the packets. You'll find the same problem with every other client out there.
It's futile, so we don't bother. Anyone who does bother either doesn't understand encryption or is intentionally giving you a false sense of security.
FUN EXAMPLE: Use Firefox? Tools -> Options -> Security -> Saved Passwords -> Show Passwords.
What's that? You use a Master Password?
Sorry.