Microwave emits loud popping noises and flashes when certain foods are cooked, even without metal present.

User-level checks:

• Stop the microwave immediately when loud popping or flashing occurs.
• Inspect the food and container; discard if burnt or damaged.
• Clean the interior thoroughly, especially around the grill element and waveguide cover.
• Use microwave-safe containers and cover foods with a vented lid or microwave-safe cover to reduce splatter.

Note: If popping and flashing occur even with simple loads like water in a plain glass, discontinue use and have the unit inspected for internal arcing issues.