This happened in 2013, in my first company. I joined the company as a Java developer and worked on some projects for a few months. Around November I was asked to work on a project that was built with Adobe Flex and ActionScript. As I started working with these technologies I learned more about them. I was happy about the fact that I was contributing to the company's growth. But I really felt that the UI should have been built with HTML, CSS and JavaScript instead of Flex. It had a lot of limitations and complexities. And I never liked .mxml to .swf compilation process. Soon I proposed to build the new UI using HTML, CSS, AngularJS and also built some prototypes. It was liked by everybody, but sadly never went live.
Working on Flex was out of my comfort zone, but I went ahead and delivered the code. Although I am not a big fan of ActionScript, I learned a lot about best practices, code organisation, concepts like two way data binding etc by reading existing AS code. Eventually, I got the chance to build the app using newer technologies. So, all in all it was a good experience. Every software engineer at some point will need to get out of their comfort zone and work on something different. You may not like the tech, but you will always learn something new.