I have never been asked this question, but I know some people who ran into it. That means you should at least give it a little thought so you can think of a good answer ahead of time. The best way to answer this question is to select a job that is most similar to the job that you are applying for. For example, if a person who is applying to be a financial analyst says their favorite job was being a salesman, then the answer is basically useless and not effective at all. Rather, you should say that you like your last marketing job because you have passion for it and you really enjoy it. Many people fail interviews based on lack of enthusiasm. So make sure you show them that you love the job you are applying for.
This answer is brief but effective. It states that this person loves marketing. The second part of the answer is basically answering a question before it is asked. If you love your job, why are you leaving? You can answer this in several ways, but my example is using the excuse of wanting to work for a larger company because it shows that I want to take the next step in my career. It shows that I want to grow and that I want to go to bigger and better opportunities. Basically, it is showing a little ambition without saying it directly.
Learn English speaking much FASTER by downloading the TalkEnglish Offline Package and submerge yourself with over 8,000 audio files and over 800 pages of lessons! Then you can study without Internet connection and also listen to audio files using your MP3 player at any time. Go to the English Download page and download today!