Having great success over a period of time or showing a sudden burst of energy. This idiom can be used in many situations.
It can refer to a burst or sudden rise to stock prices, for sports results, a sudden burst of activity (for these situations it seems to have positive connotations) and for heavy alcohol consumption.
The team has been on a tear in recent weeks.
The economy is on a tear, but can it last?
The price of gold has been on a tear recently
‘Why is he drinking so much?’ ‘He had some bad news earlier and he’s been on a tear since then.’