I learned of the position when a former student at my university and now their employee gave a presentation in class about the lab and the projects they were working on. At the end, she gave contact information to anyone interested in a summer internship. I contacted the person in charge of hiring and we arranged for me to do an on-site interview.
The interview was basically a tour of the lab, the equipment, and projects they did. During the tour he subtly asked some basic technical questions to gauge my knowledge. Then, at the end he asked what I thought of the projects. He also asked me some questions based on my resume.
This was my first ever job interview so I did not prepare at all. I struggled to answer the most basic technical questions and I didn't really pay much attention to the presentation or the tour so I couldn't say anything specific. I think he saw that easily.