Viewing fields
A popup will show if you hover a URL of a project for more than 0.75 seconds. After leaving the popup, it will disappear in a short time.
The hover is scroll-able and re-sizeable, so you can view as many fields as you want.
This functionality is enabled in Dashboards, Issue Pages, Boards and other Jira pages.
Issue previews are possible in Confluence and Bamboo also! See Issue Preview for Confluence user guide and Issue Preview for Bamboo user guide