From a human resources perspective, we're trying to find out the most information in a short period of time and match the best candidates for current or future positions.
"Tell me about yourself" is one of the frequently asked questions. We're looking to see how your experience, interests, and career aspirations fit into our organization and the position you have applied for.
Questions that relate around your past experience most likely will indicate how you will do in the position you have applied for. There have been behavioral studies that back this up.
"What do you do in your free time or what are your hobbies?" These both give us an idea if you are creative, intellectual, etc. For example, a person that likes to play chess is generally someone that may be detailed and thinks analytically.
Questions that arise about what you are planning to do in five or 10 years may indicate to the recruiter if the candidate has done his/her homework about the organization and the job opportunities within the company. We don't generally want to hire people that are going to job-hop or just test the waters to see if they are going to like working in a particular company. Hiring employees and training them is expensive. We want to invest resources in people that are going to add value and stay with the organization and help it to be competitive in the marketplace.
People are some of the greatest assets in the organization and finding a really good fit for the organization and yourself are a key interest for both of us. Do your homework about the organization you are interviewing with and the position. Most job candidates do not do this. Those that do and have researched well, have already set themselves above other job candidates.