The Burp Suite tool included with Kali Linux 2.0 (after apt-get update && apt-get upgrade && apt-get dist-upgrade) is 1.6.31 while the latest release is 1.6.32. 1.6.32 had the following changes:

There is a new option in the Proxy to set the "Connection: close" header on incoming requests. Setting this header in requests can speed up the processing of the resulting responses from some target servers. The new option is on by default.

When generating the CA certificate used by the Proxy, Burp now uses a 2048-bit key if that is supported by the platform, and fails over to a 1024-bit key if not. Some modern clients are rejecting certificates that use a key length shorter than 2048 bits. If you encounter this problem, you can tell Burp to generate a new CA certificate at Proxy / Options / Proxy Listeners / Regenerate CA certificate, and you will need to install the regenerated certificate in your browser in the normal way.