Are you talking about a glass cook top? If so I use a single edge razor blade to remove the burnt on bits off of the top, then put a hot wet towel on it, and scrub anything remaining off with a plastic round scrubbie. Then I do a layer of cooktop polish like Maquires, let dry and buff.
Electric, glass or gas?
On enamel, I will use a soap scum remover such as scrubbing bubbles. That would not be good for a ceramic smooth top, though. On ceramic, I use a cream specifically made for smooth tops. Apply a quarter sized drop. Then use a lot of water, nylon white scrubby and/or NEW razor blade (emphasis on using a new blade) to scrub the offending spots. Let sit, then repeat while it's all softened. Then polish dry (no rinsing)