I’ve used a two button setup for this situation. Each button is just a “Open Hyperlink”.
First, create an “Open” button with the following code:
Concatenate(thisRow.Url(),"&modal=true")
Next, create your “Close” button that you can display on the popup, but hide in the table view:
thisTable.Url()
The “Close” button just links to the table you came from, so it acts to close the popup window.