When we think of expanding our blog or posting different content other than your niche so here is a solution that you can make a new blog with that niche and give it a subdomain under your main domain. For example recently I have decided to post some contents other than Technology or Science then I worked on a new blog and attached it to the subdomain under my main domain. Here are two subdomain which I use for my blogs of different than blogging and tech niche : http://mix.technogeekzone.com/ and http://sci.technogeekzone.com/
How To Setup Up Subdomain in Your Main Domain:
To setup your subdomain for example blog.maindomain.com all you need to do is create a CNAME on your domain host and point it to your webhost.
Here I am taking help of Godaddy to point subdomain to my blogger Blog
First create a CNAME recored like in below picture in your domain host such as Godaddy.com or in any:
Then Go to your Blogger Dashboard and navigate to the following
> Now provide the URL blog.yourdomain.com save the Settings If you get any error then try after sometime to update that CNAME.
Make sure to these things after adding your Sub Domain
Make double sure that after applying subdomain is working alright or not. If you main domain it not opening with domainname.com but open with www.domainname.com then go to your website or blog and check that main domain is set to redirect domainname.com to www.domainname.com.