iPhone-Android texting compatibility
This is normal functionality and has been present on the original iPhone OS on the very first iPhone back in 2007.

What you are seeing is that the iPhone is allowing you to send messages that are longer than the SMS limit, and when you do that it automatically splits the message into the number of SMS messages required to send your message.

If your recipient has an iPhone, they just see the original un-split message as the iPhone puts it back together for the recipient.  Other devices, such as your friend's Android device, just show the discrete SMS messages in the order they were sent.