In a small bowl whisk together the brown sugar, honey, hot water, and a pinch of salt until combined. Place the pineapple in a gallon-sized zipper-top bag and add the brown sugar mixture. Seal the bag and shake it until the pineapple is evenly coated. Let the pineapple sit at room temperature for 15 minutes.
While the pineapple sits at room temperature, preheat the grill on high. At the end of 15 minutes scrape the grates and then lightly oil them with canola oil.
Place the pineapple slices on the grill and grill for 2-3 minutes, or until heated through and grill marks appear. Flip the pineapple, and grill for another 2-3 minutes. Serve.