There could be different approaches, depending on how you implemented the popup. For example, you could
a) emit the entire popup in every row and make it invisible initially. Then simply show/hide it based on JavaScript events.
b) you can emit the data you interested in in every row, also invisble (let's say using inputHidden fields) and then use the data when building the popup
c) you could use ajax to get the data when needed from the server. This is easy to do with RAD7 for instance, see here for an example: